Evacuating electric lamps



(No Model.)

E. P. THOMPSON.

EVAGUATING ELECTRIC LAMPS.

No. 383,676. Patented May 29, 1888.

INVENTUH. Edward f. Wmsom UNITED STATES PATENT Enron.

EDWARD P. THOMPSON, OF ELIZABETH, N EVV JERSEY.

EVACUATING ELECTRIC LAM PS.

SPECIFICATION forming part of Letters Patent N0. 383,676, dated May 29, 1888.

Application filed April 15, 1887. Serial No. 234,969. (No model.)

To aZZ whom it may concern.-

Beit known that I, EDWARD P. THOMPSON, a citizen of the United States, residing in Elizabeth, in the county of Union and State of New Jersey, have invented certain new and useful Improvements in Evacuating Electric Lamps, of which the following is a specification.

The invention relates to a method of and apparatus for evacuating'the globes of incandescent electric lamps.

The object of the invention is to provide means for increasing the vacuum which can be obtained by the former process of evacuation.

The invention consists, in general terms, in applying to the vacuum apparatus a series of incandescent electric-lamp globes,and a device for heating the globes, consisting of resistanceconductors, and an evacuated chamber connected with the globes containing the conductors, and in placing the conductors in an electric circuit.

The invention will be described in connection with the accompanying drawings, in which- Figurel illustrates an apparatus adaptedto carry out theinvention, and Fig. 2 illustrates a modification.

Referring to the figures, A represents a suitable inclosing-case for retaining heat, and it is preferably placed around the globes B B of incandescent electric. lamps, after they have been exhausted by the usual processes, and after the filaments have been heated for the purpose of aiding in expelling gases therefrom during the process of evacuating. The electric current from a generator, K, may be employed for thus heating the filaments; but this may be withdrawn from the filaments at this stage. While the evacuating-pump G is still being operated for the purpose of withdrawiug the atmosphere in the usual manner, the air in the inclosing-case A and the glass of the bulbs and the evacuating-tube E are heated to a very high temperature. The heat may be applied by means of suitable gas-burners such,for instance, as Bunsen burners as shown at H. These are applied to an extension, e, of the tube E, this extension being preferably of thick glass. This extension e passes within a tube, a, extending from the lower portion of the case A, and a hood or sleeve, 6, surrounds this tube. The flame from the burners passes in contact with the extension a within the hood 6', thus heating the extension 0 to a red heat.

This heat is conveyed to the atmosphere surrounding the globes B and raises them to a very high temperature. The rarefied gases within the bulbs is thus heated and its press-- retain the heat a considerable time, and as it gradually cools the lamps are allowed to cool slowly, thus tempering the glass. The lamps are sealed off in the usual manner after they have been cooled, and the case A is removed.

The heat may be applied by other means than the burners H-as, for instance, an electric heater, H, may be employed. This con sists of a series of conductors, h, having high resistancesuch, for instance, as carbon rods placed within a metal casing, h, which is placed in the extension 0, and in this manner the conductors h are in a high vacuum at the time that they are connected in the circuit with a generator, k, or other suitable source of electricity.

It is evident that the heat may be applied with useful effect from the beginning to the end of the exhausting process.

I claim as my invention The combination, with a vacuum. apparatus and a series of incandescent-electric-1amp globes connected therewith, of a device for heating the globes, consisting of a series of resistanceconductors, an evacuated chamber connected with the globes containing the conductors, and means for placing the conductors in an electric circuit.

In testimony whereof I have hereunto subscribed my name this 1st day of April, A. D. 1887.

EDWARD r. THOMPSON.

Witnesses:

DANL. W. EDGECOMB, CHARLES A. TERRY. 

